Kinematic Analysis And Optimal Design Of A Novel 3T1R Parallel Manipulator

As one of the most important branch of the lower mobility parallel manipulator(PM),PM with three translational and one rotational degrees of freedom(Dof)have much potential in industry field.In this paper,a novel 2-(RRR)~2RH PM with 3T1R Dofs is proposed.A detailed discussion about this PM is presented including the kinematics,performance evaluation,elastostatic stiffness,and an optimal design.The main contents are as followsFirstly,a virtual model of this PM is established using the software SolidWorks.With the fixed coordinates set appropriately,the mobility analysis on the PM can be worked out.It is shown that the PM has three translational and one rotational Dofs as expect.Given the architectural parameters of the PM,the direct kinematic analysis and the inverse kinematic analysis are both discussed by solving the close-loop vector equations of each limb.The Jacobian matrix and velocity equations are then obtained by taking differentiation of the inverse kinematics equations.The condition of the singularity is obtained and singularity configurations of the PM can be listed based on the Jacobian matrix.Considering the length of parameters and the range of inputs,the reachable workspace of the PM is obtained through iterative algorithm in software Matlab.The reachable workspace of the PM is set of points which the end effecter can attain.A kinematic simulation method is applied to verify the result above.At last,the condition number which based on Jacobian matrix is chosen as the performance index to judge whether the candidate PM is conform the demand.An optimal design of the PM is presented and the PM with best kinematic performance is obtained.The optimization method in this paper,which proposed by Liu,has advantages in efficiency and accuracy.After the optimization,the stiffness analysis about this PM is studied.The results above prove that the 2-(RRR)~2RH PM has the potential in many industry applications.It also offer support for the dynamic analysis and the kinematic control of the PM in the future work.